Bug: TUI hangs silently when /tmp is mounted noexec (dlopen of libopentui.so fails) #26136

Description

/tmp on my machine is mounted with noexec (Ubuntu corporate hardening — CIS-style fstab line with nosuid,nodev,noexec). When I run opencode, the TUI hangs forever. Nothing visible. With --print-logs --log-level DEBUG the cause shows up:

ERROR ... service=default e=Failed to initialize OpenTUI render library: Failed to open library "/tmp/.f9ef37f75ffbafff-00000001.so": /tmp/.f9ef37f75ffbafff-00000001.so: failed to map segment from shared object rejection

Bun unpacks libopentui.so into $TMPDIR (defaults to /tmp) and then dlopens it. With noexec, mmap can't grant exec perms on the segments, so dlopen fails. The TUI catches the error but never produces user-visible output, hence the silent hang.

opencode run "..." works because it doesn't load the TUI shared library.

#5175 covered the same problem and was auto-closed after 90 days of inactivity; maintainer comment there says to open a new issue if still relevant. Same root cause as #3765, #4605, #6080.

Workaround that works today:

BUN_TMPDIR=$HOME/.cache/opencode-tmp opencode

Plugins

none

OpenCode version

1.14.40

Steps to reproduce

1. add tmpfs /tmp tmpfs defaults,rw,nosuid,nodev,noexec,relatime 0 0 to /etc/fstab and reboot (or any Lynis/CIS hardening that does this)
2. confirm with findmnt /tmp -no OPTIONS (should contain noexec)
3. run opencode
4. hangs with no prompt

Operating System

Ubuntu 24.04 LTS, kernel 6.17

Terminal

GNOME Terminal (also reproduces in tmux, alacritty, plain TTY)